Well, in my mind, running for the nearest friendly base is a very reasonable thing to do. Consider this for a moment, if you get mugged while standing outside a police station, would you pay up or run for safety?
It is the pirates job to ambush traders somewhere where they cannot easily get to a friendly base. If you catch me right outside a base you can bet Ill run for safety. If you catch me on my own far away from any friendly base, Id rather pay than lose my cargo.
Of course, the demand must also be reasonable. If Im hauling 1 million worth of cargo and you ask for 5, Ill take my chance and run since my cargo is not worth nearly as much as the credits.